1. Field
The present disclosure relates generally to composite structures and, in particular, to joints between composite structures. Still more particularly, the present disclosure relates to a method and apparatus for joining two composite structures using a reduced amount of adhesive.
2. Background
Composite structures may be used to form various types of objects. These objects may include, for example, without limitation, a fuselage, an overhead bin in an aircraft, an automobile structure, a storage container, a part for a vehicle, a piece of equipment, a tool, a fastener, a beam, a support structure, and/or other types of objects.
In some cases, two composite structures may be attached to each other to form a joint. As one illustrative example, a first composite panel may be attached to a second composite panel to form a joint. As used herein, a “composite panel” may be comprised of a honeycomb core sandwiched by two skins. A “honeycomb core”, as used herein, may be a layer of material comprising an array of hollow cells defined by vertical walls. These cells may have, for example, without limitation, a cylindrical shape, a cuboidal shape, a prism-type shape, a hexagonal shape, or some other type of shape.
Some currently available methods for forming a joint between two composite panels may include fabricating one or more tab sections at the end of a first composite panel and fabricating one or more slots, respectively, at a first surface of a second composite panel. Typically, the tab sections may be fabricated by cutting away a portion of the first composite panel at the end of the first composite panel. Each tab section may have a total width that includes the widths of the two skins and the width of the core of the first composite panel.
The first composite panel may be positioned relative to the second composite panel such that the tab sections at the end of the first composite panel can be inserted into the corresponding slots in the second composite panel. Adhesive may be applied within the slots in the second composite panel prior to insertion of the tab sections within the slots. When the tab sections of the first composite panel are inserted into the corresponding slots in the second composite panel to form the joint between these two composite panels, the adhesive may allow the tab sections to fixedly adhere to the insides of the slots.
However, with these currently available methods, the amount of adhesive required for forming the joint may be greater than desired. For example, without limitation, each slot into which a corresponding tab section is inserted may have a width that is substantially equal to the width of the corresponding tab section. Additionally, the slot may have a depth that is substantially equal to the height of the corresponding tab section.
Adhesive may need to be applied to the slot such that the adhesive fills substantially the entire volume of the slot. The weight added by the amount of adhesive needed to fill the volume of the slot may be greater than desired. Further, when adhesive is applied such that the adhesive fills substantially the entire volume of the slot, insertion of a tab section into the slot may cause spillover of adhesive over the first surface of the second composite panel. The time and/or effort required to clean this excess adhesive may be greater than desired.
In some cases, the sizes of the slots formed in the second composite panel may reduce the structural integrity of the second composite panel outside of selected tolerances. Additionally, the sizes of these slots may cause a second surface of the second composite panel that is opposite to the first surface of the second composite panel, on which the slots are present, to have an undesired visual appearance.
For example, without limitation, locations on the second surface corresponding to the locations of the slots within the second composite panel may appear darker and/or lighter relative to the rest of the second surface of the second composite panel more than desired. In some cases, these darker and/or lighter locations on the second surface of the second composite panel may reduce the overall aesthetic appeal of the second composite panel. This reduction in aesthetic appeal may be undesirable when the second surface is used as, for example, without limitation, a decorative surface. Additionally, locations on the second surface corresponding to the locations of the slots within the second composite panel may be raised or dimpled in an undesired manner. Therefore, it may be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.